ASTM D5763 Standard Test Method for Oxidation and Thermal Stability Characteristics of Gear Oils Using Universal Glassware
6. Apparatus
6.1 Heating Bath, or Block, thermostatically controlled, capable of maintaining the oil sample in the oxidation cell at a uniform temperature of 120 +/- 1°C and large enough to hold a minimum of two oxidation cells and sufficiently deep to allow approximately 120 mm of the test tubes to extend above the heating liquid or block. The heating block is further described in Test Method D4871.
6.2 Oxidation Cell, consists of borosilicate glass; a 38- mm inside diameter and a 300 +/- 5-mm length is required.
NOTE 2 - While the round-robin test used the oxidation cell from a specific equipment manufacturer in determining the precision statement, the test method permits the use of other oxidation cells that meet the requirements of 6.2.
6.3 Air Delivery Tube, a borosilicate glass tube having an inside diameter of 5 mm and a minimum length of 320 mm, with the lower tip cut at a 45° angle.
NOTE 3 - The oxidation cell and delivery tube are further described in Test Method D4871.
6.4 Flowmeters, one for each oxidation cell, capable of measuring an air flow of 3 L/h +/- 0.5 L/h.
6.5 Air Dryer - Before being supplied to the flowmeters, the air shall be passed through a drying tower packed with indicating grade anhydrous calcium sulfate or equivalent. The quantity of desiccant should be sufficient to last for the entire test. It is recommended that the drying tower be filled with fresh desiccant prior to the test.
6.6 Filter, glass fiber, 2.8-µm porosity, 47 mm in diameter.
6.7 Balance, electronic, top-loading, capable of weighing to the nearest centigram (0.01 g) and having the capacity to weigh up to 2000 g.
6.8 Filter Holder, 47 mm, consisting of a borosilicate glass funnel and a funnel base with a coarse-grade fritted glass filter support or stainless steel screen support such that the filter can be clamped between the ground glass sealing surfaces of the funnel and its base by means of a metal clamp.
6.9 Oven, explosive-proof, capable of heating from 50 to 60°C and of a sufficient size to hold oxidation cells.
6.10 Thermometer, ASTM solvent distillation thermometer having a range from 98 to 152°C and conforming to the requirement for Thermometer 41C in accordance with Specification E 1.
6.11 Vacuum Source, to provide pressure reduction to 100 +/- 5 mm Hg absolute pressure.
7. Reagents and Materials
7.1 Air Supply, dried air, oil free, at constant pressure to permit 3 L/h air flow through the system. House air supply or pressurized air cylinders can be used.
7.2 Calcium Sulfate Desiccant, Anhydrous, indicating grade (desiccant that changes color when it nears saturation with water). Desiccants equivalent to calcium sulfate can be used.
7.3 Heptane, minimum purity - 99.75 %. (Warning - Heptane is flammable and a health hazard.)
